In order to investigate the effects of the physical and dyeing properties on the aminolysis of biaxially strectched poly(ethylene terephthalate) (PET) film, PET film was aminolyzed in 50n ethylendiamine and ethylamine aqueous solution at 4$0^{circ}C$, 5$0^{circ}C$ and 6$0^{circ}C$. The cracks observed on the surface of PET films accompanying aminolysis were caused by degradation and dissolution of polymer chain and difference in the residual stress between skin layer and core phase. The degree of degradation aminolyzed PET films increased with increasing the aminolysis time and temperature. The moisture regain of aminolyzed PET films increased with increasing the degree of degradation. The dye uptake and diffusion coefficient of disperse dye in PET film treated with EDA and EA solution were increased with increase of degree of degradation. And the PET film treated with EDA solution was more effective in improvement of absorption and dyeing properties than EA solution.